/Engine/Source/Editor/MaterialEditor/Public/MaterialEditingLibrary.h
Get the output name of input node connected to MaterialExpression from an active material editor
static bool GetInputNodeOutputNameForMaterialExpression ( [UMaterialExpression](API\Runtime\Engine\Materials\UMaterialExpression) * MaterialExpression, [UMaterialExpression](API\Runtime\Engine\Materials\UMaterialExpression) * InputNode, [FString](API\Runtime\Core\Containers\FString) & OutputName )